This application claims the benefits of Japanese Application No. 11-202061 which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a one-way clutch apparatus for constituting an automatic transmission, or the like, for a car, and more specifically, to a technology for achieving smooth lubrication, etc., with respect to frictional engagement means.
2. Related Background Art
Generally, an automatic transmission for a car comprises a planetary gear mechanism capable of 3 to 5 speed change, in addition to a torque converter serving as a fluid coupling, so as to conduct the speed change by properly fixing or releasing the constituent elements of the planetary gear mechanism (a sun gear, a planetary gear, etc.) with frictional engagement means such as a clutch or a brake. As the frictional engagement means to be assembled in the automatic transmission, a wet-type multi-disc type means which comprises friction discs or plates and separator discs or plates alternately provided therein is employed, with some exceptions of band-type brakes. For the pressure contacting (frictional engagement) of the both plates, pressure oil from a gear change control oil pressure circuit is employed. Some of such frictional engagement means incorporate a one-way clutch apparatus therein, so as to freely rotate a gear shaft, or the like, in one direction, thereby realizing easier gear change control.
FIG. 7 is a longitudinal sectional view for showing the essential part of a conventional one-way clutch apparatus which is incorporated in the frictional engagement means. In FIG. 7, the one-way clutch apparatus 1 is comprised of an inner race 5 on which a lubricating oil supply bore 3 open to the outer peripheral surface is formed, an outer race 7 which is supported to be coaxial and relatively rotatable with respect to this inner race 5, a one-way clutch mechanism 9 of a sprag type which is interposed between the inner race 5 and the outer race 7, and a pair of retainers 11 which are fixed to the both ends of the outer race 7 for regulating an axial movement of this one-way clutch mechanism 9. In this one-way clutch apparatus 1, the outer race 7 is integrally formed with a hub 15 of a wet-type multi-disc clutch which is provided outwardly in the radial direction, and a spline 27 with which a friction plate, or the like, is engaged is formed on the outer peripheral surface of the hub 15. In FIG. 7, a member denoted by a reference numeral 29 is a Zytel washer 29 which serves as a sliding bearing to be contacted with a side surface of the retainer 11 in a sliding manner.
The one-way clutch mechanism 9 is comprised of a large number of sprags 31 each serving as a torque transmitting element, a ribbon spring 33 for retaining the sprags 31 and, at the same time, biasing the sprags 31 in the direction of engagement, an outer retainer 35 for annularly retaining the ribbon spring 33, an inner retainer 37 for suppressing an excessive inclination of the sprags 31 together with the outer retainer 35, and a pair of end bearings 39 for retaining the both retainers 35 and 37 with a predetermined space therebetween, so as to ensure an operation of the sprags 31. Elastic claws 41 which are contacted with the outer race 7 in a sliding manner are formed at several positions on the outer retainer 35. An appropriate drag torque is generated between the outer race 7 and the one-way clutch mechanism 9 by these elastic claws 41, so as to prevent a sliding at the time of engagement of the one-way clutch mechanism 9 and, at the same time, to prevent local wear from occurring in the outer race 7 and the inner race 5.
In the one-way clutch apparatus described above, supply of the lubricating oil to the frictional engagement means is not conducted smoothly, so that wear of the friction plate, and the like, may be brought about.
The one-way clutch mechanism 9 presses the outer race 7 and the inner race 5 by means of the sprags 31 at the time of engagement, while sliding contacting with the inner race 5 at the time of idling. When the one-way clutch mechanism 9 and the outer race 7 are relatively rotated with each other at the time of vibration or engagement, the elastic claws 41 sliding contact with the inner peripheral surface of the outer race 7.
Accordingly, the lubricating oil is supplied by pressure into the one-way clutch mechanism 9 from the lubricating oil supply bore 3 of the inner race 5, and a lubricating oil film is formed between the constituent elements of the one-way clutch mechanism 9 and the outer race 7 and the inner race 5, so as to prevent wear of these members.
Incidentally, in a one-way clutch apparatus for an automatic transmission, the frictional engagement means is provided on the outer peripheral side of the outer race, so that lubrication of the constituent elements thereof (the friction plates, the separator plates, and the like) becomes required. However, in the conventional one-way clutch apparatus 1 described above, the lubricating oil which flows into the one-way clutch mechanism 9 is blocked by the retainer 11 and the Zytel washer 29, so as to prevent the lubricating oil from flowing into the frictional engagement means. For this reason, the frictional surface of the friction plate, or the like, is worn in a comparatively short period of operation, and it is feared that the engaging performance of the frictional engagement means may be damaged in the comparatively short period of operation. In order to solve this problem, it is considered to provide a lubricating oil supply path separately. In this case, however, the processing cost may be increased or the axial length of the automatic transmission may be extended.
The present invention is contrived taking the circumstances described above into consideration, and the object of the invention is to provide a one-way clutch for achieving smooth lubrication with respect to frictional engagement means, while employing a comparatively simple structure.
In order to solve the above-described problems, the present invention provides, a one-way clutch comprising an inner race on which a lubricating oil supply path open to the outer peripheral surface is formed, an outer race which is supported to be coaxial and relatively rotatable with respect to this inner race, a one-way clutch mechanism which is interposed between the inner race and the outer race, and a pair of retainers fixed to the both ends of the outer race for regulating an axial movement of the one-way clutch, wherein a lubricating oil passage is formed between at least one of the retainers and the outer race for guiding the lubricating oil in the radially outward direction.
According to the present invention, the lubricating oil which flows into the one-way clutch mechanism passes through the lubricating oil passage and is supplied to the wet-type multi-disc clutch, or the like, which is provided outward in the radial direction of the outer race. The lubricating oil is then used for lubrication of the friction plates, etc.
Also, in the one-way clutch of the present invention, one of the retainers may be extended from a hub of frictional engagement means or mechanism provided outside in the radial direction of the outer race. According to this preferable feature, it is possible to realize weight reduction or cost reduction of the apparatus by molding the hub of steel plate by pressing, for example, and by forming the retainers integrally with the hub.
Further, in the one-way clutch of the present invention, the other of the retainers may be made of resin material and have an engagement portion engaged with an annular groove formed on the outer periphery of the outer race. According to this preferable feature, it is possible to enhance the mass productivity and to realize easy attachment or detachment of the retainers to or from the outer race by molding, for example, the retainers of synthetic resin by injection molding. Further the Zytel washer may be omitted, depending on the lubricating performance of the material.